Compilare: user.cpp: In function ‘int BFS()’: user.cpp:24:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:55:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[N].size(); ++i) ^ user.cpp:45:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d",&N,&M); ^ user.cpp:48:40: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d %d",&x,&y,&z); ^